Nowadays, semiconductor memories are utilized everywhere such as in main storages of large computers, personal computers, home appliances and mobile telephones. The NAND flash memories (NAND-type Flash EEPROM) are growing in the market, and various memory cards (SD, MMC and CF cards) or USB memories which store information including images, movies, sounds and games are used as storage media for digital cameras, digital video cameras, music equipment such as MP3, mobile telephones and mobile PCs and as storage media for such as digital TVs.
If a NAND flash memory of several hundred GB can be realized, it is also possible to replace a HDD for a PC, with this NAND flash memory. Flash-EEPROM type non-volatile memories mainly include a NOR type and a NAND type, and, although the NOR type is used to store command codes of a mobile device having about the thirteenth power of ten for the number of high speed Read and Read, it has a narrow effective bandwidth and is not suitable for recording files. By contrast, because the NAND type can realize higher integration compared to the NOR type, and, moreover, can perform Burst Read and has a wider effective bandwidth of Write even though an access time is, for example, 25 us and is slow, can program and erase a greater number of bits at a time even though an erase time is about several ms and is slow, and can import write data by way of Burst and program a greater number of bits at a time and thus has a wider effective bandwidth, and therefore the NAND type is widely used in the above market.